Water Sampling

A Graham County Environmental Health Specialist will perform a bacteriological analysis on water samples from both public and private water systems. Samples are examined for the presence of the coliform group of bacteria, which are indicators of fecal contamination.

Public water system samples are submitted to the North Carolina State Laboratory of Public Health.

Selenium - MCL = 0.05 mg/L. It is an essential trace nutrient, but may be toxic above trace levels. Natural levels in groundwater may be due to soil types. Selenium may be leached from coal ash and fly ash at electric power plants that burn seleniferous coal.

Silver - MCL = 0.10 mg/L. Exposure to silver in drinking water may cause argyria (a discoloration of the skin). Health effects are only cosmetic.

Thallium - MCL = 02 mg/L. Affects the brain, kidneys, and liver. Its presence may be associated with electronics or glass industries.

Total Dissolved Solids - MCL = 500 mg/L. Waters with high dissolved solids are unpalatable and may be unsuitable for many industrial applications.

Zinc - MCL = 5 mg/L. Zinc may cause a bitter astringent taste and opalescence in alkaline water. Most often enters the water supply through the deterioration of galvanized iron pipes.

Sample analysis time will vary from one day to thirteen days, depending upon the number of parameters requested for the sample. The submitter should receive a copy of the analytical results within three weeks of the date of sample collection. Public and private water system laboratory reports are held for five years, and then destroyed.

Nitrate

Nitrate - MCL = 10 mg/L (as nitrogen). Serious poisonings in infants have occurred following ingestion of well water containing nitrate nitrogen at concentrations greater than 10 mg/L. This problem is known as methemoglobinemia and is generally confined to infants less than three months old. The presence of nitrates is usually due to animal wastes and fertilizers. Boiling water does not remove nitrates but instead concentrates them.

Nitrite

Nitrite - MCL = 1mg/L (as nitrogen). Nitrite is the actual etiologic agent of methemoglobenemia. It results from oxidation of ammonia or reduction of nitrates. May occur in natural water or water distribution systems.

Pesticide sampling may be important in areas where someone is applying products to kill pests, such as rodents, mites, mosquitoes, etc. Herbicide sampling may be important in areas where someone is applying products to kill weeds and other plants that grow where that grow where they are not wanted.